Field of the Invention
The present invention relates to an openable vehicle roof structure provided with an openable roof including an expandable and retractable awning frame, and an awning cloth for covering the outside of the awning frame, and capable of openably covering a vehicle body upper portion by the openable roof.
Description of the Related Art
Generally, an openable roof for openably covering a vehicle body upper portion is provided with an awning frame which is expandable and retractable with respect to a vehicle body, and an awning cloth for covering the outside of the awning frame.
For instance, an openable roof structure disclosed in Japanese Unexamined Patent Publication No. 2006-232045 (hereinafter, called as Patent Literature 1) is configured such that an awning frame is provided with a top frame, which is laterally provided on a front end of the awning frame, and which is attachably and detachably fixed to a front header on the vehicle body side (a member for supporting the upper edge of a front window glass); a pair of left and right side frames, which are mounted on left and right sides of the top frame, and which extend while curving along the opening edge of each door glass of a vehicle body; a pair of left and right control links, each of which controls folding operations of a front frame and a rear frame constituting each of the side frames; and three awning bows disposed to bridge between the paired side frames. In the following, a state such that the openable roof is expanded to cover the vehicle body upper portion is called as a roof expanded state, and a state such that the openable roof is folded and accommodated in a vehicle body (a state that the vehicle body upper portion is opened) is called as a roof retracted state.
When the openable roof is in a roof expanded state, the top frame is engaged with a striker on the front header side by a fixing device located on a lower middle portion of the top frame in the vehicle width direction. The awning cloth is stretched in such a manner as to cover an upper side portion extending in the vehicle width direction of each of the awning bows, and the top frame. A lower rear portion of the awning cloth is mounted on a rain rail as a vehicle body member. In this configuration, a downward tensile force is exerted on the awning bows from the awning cloth.
In the openable vehicle roof structure disclosed in Patent Literature 1, when a roofline in a roof expanded state (namely, a stretched configuration of the awning cloth) is formed in such a manner that the roof is moderately inclined toward a back window, if the awning bows are largely folded toward the vehicle front side, a bending moment in the folding direction is generated in the awning bows due to the tensile force exerted from the awning cloth. Therefore, there is room for improvement in terms of stability and durability of the awning bows.